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Article 

Pathological findings of an eye anomaly in Randall's threadfin 
bream Nemipterus randalli Russell, 1986 from the Mediterranean 
Sea (Antalya Gulf-Türkiye) 
Şükrü Güngör 1, *, Özlem Özmen 1 and Deniz İnnal2 

1 Burdur Mehmet Akif Ersoy University, Faculty of Veterinary Science, Istiklal Campus, 15030, Burdur, 
Türkiye; ozlemoz@mehmetakif.edu.tr  

2 Burdur Mehmet Akif Ersoy University, Department of Biology, Istiklal Campus, 15030, Burdur, Türkiye; 
denizinnal@mehmetakif.edu.tr   

* Correspondence: sukrugungor@mehmetakif.edu.tr ; Tel.: +90 248 2132183   
 

Abstract: Genetic, environmental and nutritional conditions seriously affect the health of natural fish stocks. In addition, increasing 
human pressure on aquatic systems in recent years is threatening fish populations. Under the influence of increasing environmental 
pressures and other factors, different types of abnormalities are observed in fish. Among these, morphological abnormalities, 
pigmentation abnormalities, eye abnormalities, visceral abnormalities and reproductive abnormalities are commonly observed. 
There is limited information on eye abnormalities in Mediterranean fish species. In the present study, the body abnormality observed 
in a trawl-caught specimen of Randall's threadfin bream, in which the eyes were missing, and its causes are reported and the 
pathological findings discussed. 

Keywords: Red Sea; Lessepsian; Randall's threadfin bream; ocular abnormalities 
 

1. Introduction 
Several types of abnormalities have been reported in fish. These abnormalities 

include morphological abnormalities, pigmentation abnormalities, ocular abnormalities, 
visceral abnormalities and reproductive abnormalities[1, 2]. These abnormalities may be 
due to genetic, environmental, nutritional and stress factors. Abnormalities observed in 
fish can affect the health and quality of life of the fish in several ways. These effects can 
often have a negative impact on the fish's general physiological functions, growth rate, 
reproductive ability and even survival rate [3, 4]. Among the abnormalities observed in 
fish, ocular abnormalities have a very important impact on fish health. It is reported that 
microphthalmia, anophthalmia, cataract, abnormalities in eye size and location are 
common among eye abnormalities. Eye abnormalities in fish have been reported under 
both aquaculture conditions and from natural stocks [5].  

This paper describes the physical body abnormality observed in an individual 
(Nemipterus randalli) without its eyes, collected from the Gulf of Antalya, in the 
Mediterranean Sea, on 18 March 2024. The number of studies on the distribution and 
ecology of N. randalli in the Mediterranean has increased in recent years [6-11]. As far as 
it is known, this study is the first record of eye deformity of Randall's threadfin bream 
along the Mediterranean. Simultaneously, this report constitutes the pathological findings 
of this deformity. 

2. Materials and Methods 
2.1. Ethics statement 

Received: 25.02.2025 

Accepted: 28.02.2025 

Published: 15.07.2025 

DOI:10.52331/v30i2k31 

 

 

 

Copyright: © 2025 by the authors. 

Submitted for possible open access 

publication under the terms and con-

ditions of the Creative Commons At-

tribution (CC BY) license (http://crea-

tivecommons.org/licenses/by/4.0/). 

mailto:ozlemoz@mehmetakif.edu.tr
mailto:denizinnal@mehmetakif.edu.tr
mailto:sukrugungor@mehmetakif.edu.tr


Cluj Vet J 2025, vol 30, issue 2 56 of 66 
 

 

 This study follows all relevant international, national, and institutional guidelines for the 
collection and experimental use of fish samples. The fish species examined are not listed in the IUCN 
Red List of Threatened Species and are not classified as endangered, vulnerable, rare, or protected in 
Türkiye. Additionally, the sampling sites are situated outside of any designated protected areas, 
making an ethics statement unnecessary. 

2.2. Study design 

The specimen of N. randalli obtained from the Gulf of Antalya was caught during trawl surveys 
on 18 March 2024. Fish samples were transported directly to the lab, where measurements were made 
of their weight (total weight W to the nearest 0.1 g) and length (total length cm TL, precision 1 mm). 
The gonads were examined both macroscopic and microscopic to determine the sex. During the 
necropsy, the eyes of the fish were examined grossly and then carefully enucleated. The eye samples 
were collected, and the fish were fixed in 10% neutral formalin. Normal fish eye were also collected 
for comparison. The formalin-fixed tissues were embedded in paraffin following standard processing 
with an automatic tissue processor (Leica ASP300S; Leica Microsystems, Nussloch, Germany). Using 
a Leica RM 2155 rotary microtome (Leica Microsystems, Nussloch, Germany), serial sections with a 
thickness of 5 µm were cut. Hematoxylin and eosin (HE) staining was applied to each section, and 
each was inspected under a light microscope. The Database Manual Cell Sens Life Science Imaging 
Software System (Olympus Corporation, Tokyo, Japan) was used for microphotography. 

3. Results 

Abnormality was recorded in one specimen of N. randalli obtained from Antalya Gulf. The 
Randall’s threadfin bream specimen was obtained from with trawl surveys. The specimen had a 
normal body shape, but eyes were missing with no injury (Figure 1). The total body length was 18.4 
cm, and the total weight was 69.3 g. 

 

Figure 1. Macroscopic appearance of normal and anomalous fish, iris and pupil of the normal fish and no iris and pupil of 
anomalous fish. 



Cluj Vet J 2025, vol 30, issue 2 57 of 66 
 

 

3.1. Gross Findings 

During the macroscopic examination of the normal fish eye, a distinct yellow-orange iris and a 
prominent black pupil in the center were observed. In the eye of the anomalous fish, only scleral 
structures within the orbit were observed (Figure 1). 

Macroscopic examination of the anomalous fish's body revealed normal body appearance but 
during the opening of the abdominal cavity, the organs appeared atrophic compared the normal fish 
(Figure 2). 

 

 

Figure 2. Appearance of abdominal organs of the normal and anomalous fish. 

 



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Microscopic examination revealed that only the sclera was present in the eye. The retinal layer 
was completely undeveloped. No melanocytes were observed. Only a hypoplastic, small lens remnant 
was noted. No other ocular structures were seen (Figure3). 

 

 

Figure 3. Normal (upper row) and anomalous eyes (below row) histopathology findings. Scleral cartilages (thick arrows), and 
scleral stroma (thin arrows), normal lens of normal fish and atrophic lens in anomalous fish (stars) and retinal layer (arrowhead) in 

normal fish but no retina in anomalous fish, HE, scale bars= 200µm. 

4. Discussion 

Nemipterus randalli has a wide geographical distribution from the coasts of eastern and western 
India to Pakistan, the Persian Gulf, the Red Sea, the Gulf of Aden, East Africa, Seychelles and 
Madagascar in the western Indian Ocean [10, 12-14]. N. randalli was first recorded in Israel in the 
Mediterranean. In the following years, it showed a widespread distribution in the Mediterranean. This 
species, which has been caught in high density in the Mediterranean coast of Turkey in recent years, 
is economically utilized. It has a high economic value due to its similarity to coral species. This species, 
which has been caught in high density in the Mediterranean coast of Turkey in recent years, is 
economically utilized. 

Some abnormalities have been reported due to different reasons in the natural habitat of this 
species and in the Mediterranean Sea. Pigment anomaly was reported in the natural distribution area 
of Nemipterus [15]. Pugheadness anomaly was reported in Gökova (Muğla) populations of 
Nemipterus which introduced to the Mediterranean Sea [16]. A number of factors have been identified 
as contributing to fish abnormalities, including unfavourable abiotic conditions; and pollutants such 
as pesticides, chlorinated hydrocarbons, organophosphates, heavy metals, infectious agents, 
inappropriate nutrition and genetic factors [2, 3, 17]. 

According to Smith, Donahue [5], the abnormalities found in fish eyes include opaque or cloudy 
eyes, exophthalmia, missing eyes, hemorrhagic eyes, emboli, and gas bubbles in the eye. A number of 
factors, such as gas imbalances that cause exophthalmos, toxicants that cause hyperemia, cataract, 
retinitis, and keratitis, low temperatures and osmotic imbalances that cause cataract, on the other hand 



Cluj Vet J 2025, vol 30, issue 2 59 of 66 
 

 

nutritional deficiencies that cause cataract, retinal and corneal, diseases, parasitemias that cause 
exophthalmos, keratitis, cataract, radiation damage that causes keratitis, cataract, trauma from 
iatrogenic factors, and injuries from uncontrolled culture systems, can lead to eyes lesions[18]. When 
the abnormalities reported in this species were analysed, it was found that no eye anomaly had been 
reported before. In the study, it was determined that the eyes abnormalities one speciemen of N. 
randalli showed macroscopic and microscopic differences compared to normal individuals. It is 
thought that this situation negatively affects the fish physiologically. 

5. Conclusions 

To the best of our knowledge, this survey reports the first eye abnormalities in Nemipterus 
randalli. The causes of the eye anomaly found in N. randalli are unknown. In countries bordering the 
Mediterranean Sea, increasing human activities are changing the quality of seawater. Numerous 
physiological and morphological changes in marine organisms have been reported as a result of water 
quality. Nervous necrosis virus (NNV), which is reported to infect about 40 fish species worldwide, 
was detected in N. randalli in a study conducted in the Mediterranean Sea [19]. NNV infection targets 
the central nervous system, including the brain, spinal cord and eye. Due to the fact that the Randall's 
threadfin bream is commercial species, further studies are needed in order to assess the eye 
abnormalities in Mediterranean populations. 

Author Contributions: Gungor S.: Conception and design of the study, Gungor S., Ozmen O., and Innal D.; 
acquisition and analysis of data, interpretation of data. Ozmen O., Gungor S., and Innal D. drafting of manuscript. 
Gungor S., and Innal D. revision of the manuscript. All authors read and approved the final manuscript.  

Funding: The authors have no funding to report. 

Institutional Review Board Statement: This study follows all relevant international, national, and institutional 
guidelines for the collection and experimental use of fish samples. The fish species examined are not listed in the 
IUCN Red List of Threatened Species and are not classified as endangered, vulnerable, rare, or protected in Türkiye. 
Additionally, the sampling sites are situated outside of any designated protected areas, making an ethics statement 
unnecessary. 

Acknowledgments: The authors have no support to report. 

Conflicts of Interest: The authors declare no conflict of interest. 

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